So, I watched both OVA's and now can write a review on it.
In short: the first is about Chihiro and how he had found a book about resurrection; the second is about Aria and her strange dream (I can't write what was this dream about because it will be a great spoiler for you; for same reason I'm not writing who is Chihiro&Aria).
First OVA is like a prequel for the TV series. If you didn't watched "Sankarea" yet, I strongly recommend you to start with this OVA -- you'll free from several question and won't say "WTF?!" after the first TV ep. 10/10.
Second is so
strange and weakly connected to the main story. That is why I recommend you watch this after the TV series, but not the right after! 6/10.
Both OVA's are well-animated and have cute scenes. Quint essence of the TV series...
Nevertheless, I can't say that it's a masterpiece.
Just like I said about art. Also 9/10.
Well, well. All characters, except Aria in her dream, are shown true. True, but not great.
7/10, also due to better first and worse second OVA.
8/10. Very, very good additional episodes of "Sankarea". I like it.
If you haven't watched Sankarea yet, definitely watch the first OVA, (Episode 00), before you do. Being the prequel, it'll answer some questions you have.
Episode 00 is about 17 months earlier. Chihiro is telling a story, about memories, mostly in his perspective but also some is in Rea's. You see some more about Rea's odd relationship with her father and her mother. Chihiro goes on a holiday with his family and Ranko tags along. So you learn more about their history, too.
The second OVA, Episode 14, is best to watch after the series, as that's it's proper place. A weird girl appears under the
temple and strange things start happening. Chihiro shows he's smarter than he looks, and it all comes together in the end.
I’m writing this pretty late, so probably no1 bothers, but maybe for 1 person, it’ll help. There have been many people suggesting to watch 1st OVA (episode 00) before the ‘Sankarea’ anime, but I’d advise against that, because you might have some questions regarding the series but honestly why would you wanna have your questions answered before you even started ur anime. Just watch the 1st 12 episodes (the anime), then watch the OVA and special. Because the 1st ova tells the back story of main characters, so you will not have the ‘Beginning of an anime’ feeling anymore as you already know the main
characters’ past. So I’d recommend to refrain from watching this if you haven’t watched the anime yet. After watching ova and specials, proceed to manga (and don’t read the final (Extra) chapter of manga (56.001), refrain from reading that.) because there won’t be a second season.
This isn’t a review exactly, but here’s one if you need:
The first episode is about both the main characters past, and how one of them came across a ‘thing’ which made this whole anime possible. It’s interesting to watch because the episode flows really good.
The second (episode 14) episode is a ‘not-so-necessary episode’ I’d say, but no harm in watching. It’s about a ‘side character’. But this episode accomplishes nothing in the end, you will be asking urself, ‘why does this episode even exists?’.
There, you have it, but I do strongly recommend you to follow my advice that I mentioned at the top.